Nitrogen gas-pressure tension testing of concrete

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University of New Brunswick
Concrete is the most-used construction material in civil engineering projects in the world today due to its versatility, durability and economy. Although, tensile strengths are not usually considered in design they are important since cracking in concrete is a tensile failure phenomena and one of the most commonly cited reasons for concrete's lack of performance. There are several common methods used for estimating the tensile strength of concrete through indirect tension tests. These methods are the splitting tensile and the flexure test. As a variation to the splitting tensile test, a new test has been developed in which nitrogen gas-pressure is applied to the curved surface of a concrete cylinder to produce a tensile failure. The purpose of this study was to compare the nitrogen gas-pressure test with the flexure and splitting tensile tests. A secondary objective of the study was to compare the concrete strength results with the values given in the literature so that the relative effects of alkali-aggregate reactivity (AAR) on the various strength properties could be ascertained. Two test programs were utilized. The first test program was designed to compare the results from the three indirect tension tests using normal weight concrete of different compressive strengths. The results of this study determined that the tensile strength values obtained using the nitrogen gas-pressure test were similar to those of the flexure and splitting tensile tests. The second test program was designed to compare the strength development with time for a normal weight, lightweight and reactive aggregate concrete. The results from this study determined that the strength of the concrete decreased due to exposure to AAR. Also, the nitrogen gas-pressure tensile strength values decreased more than those values obtained using the flexure or splitting tensile tests.